ICH volume (ABC/2)
Bedside estimate of intracerebral haemorrhage volume from three CT diameters
Sources last checked: 2026-11-03
ICH volume (ABC/2)
Bedside estimate of intracerebral haemorrhage volume from three CT diameters
ABC/2 assumes an ellipsoid; irregular, lobar and anticoagulation-associated haematomas are often overestimated. Intraventricular blood is not included. Prognostic figures come from 1990s cohorts and should not by themselves drive limitation of care.
Interpretation
| < 30 mL | Broderick et al. (1993): with GCS ≥ 9, a parenchymal volume below 30 cm³ predicted 30-day mortality of 19 %. |
|---|---|
| 30–60 mL | Counts as ≥ 30 mL in the ICH score (Hemphill 2001). Broderick et al. found that only 1 of 71 patients with ≥ 30 cm³ functioned independently at 30 days. |
| > 60 mL | Broderick et al. (1993): ≥ 60 cm³ with GCS ≤ 8 predicted 30-day mortality of 91 %. |
What is the ICH volume (ABC/2)?
ABC/2 estimates the volume of an intracerebral haemorrhage from the first CT by treating it as an ellipsoid. Kothari and colleagues (1996) showed that it correlates closely with planimetric volumes and takes under a minute. Volume is the strongest single predictor of 30-day outcome after spontaneous ICH and is one item of the ICH score.
When to use it
- Spontaneous intracerebral haemorrhage on the initial non-contrast CT
- Calculating the ICH score (volume ≥ 30 mL)
- Follow-up CT to detect haematoma expansion
When not to use it
- Subdural, epidural or subarachnoid haemorrhage
- Volume of intraventricular extension (not captured)
- When software-based volumetry is available and precision matters (e.g. trial eligibility)
How it is calculated
Volume (mL) = A × B × C / 2 (A, B, C in cm)
Clinical pearls and limitations
- ABC/2 assumes an ellipsoid; irregular, lobar and anticoagulation-associated haematomas are often overestimated. Intraventricular blood is not included. Prognostic figures come from 1990s cohorts and should not by themselves drive limitation of care.
- A and B are measured on the slice with the largest haemorrhage area; C is the slice count × slice thickness in cm.
- Irregular and multilobar haematomas, typical of anticoagulation, are overestimated by ABC/2.
- Use the same method on follow-up scans when looking for expansion.
- 1 cm³ = 1 mL.
Frequently asked questions
How do you calculate ICH volume?
Multiply the largest diameter (A), the perpendicular diameter (B) and the vertical extent (C), all in cm, and divide by 2 — the result is in mL.
What ICH volume is large?
30 mL or more scores a point in the ICH score; in Broderick's 1993 cohort ≥ 60 mL with GCS ≤ 8 predicted 91 % 30-day mortality.
How is C calculated in ABC/2?
Count the CT slices showing haemorrhage, weighting slices with a much smaller area as partial, and multiply by the slice thickness in cm.
Evidence and guidelines
- Primary source: Kothari RU, Brott T, Broderick JP, Barsan WG, Sauerbeck LR, Zuccarello M, Khoury J. The ABCs of measuring intracerebral hemorrhage volumes. Stroke 1996;27(8):1304-1305.
- Broderick JP, Brott TG, Duldner JE, Tomsick T, Huster G. Volume of intracerebral hemorrhage. A powerful and easy-to-use predictor of 30-day mortality. Stroke 1993;24(7):987-993.
- Hemphill JC 3rd et al. The ICH score: a simple, reliable grading scale for intracerebral hemorrhage. Stroke 2001;32(4):891-897.
- Colmer NHC et al. Validity of intracerebral haemorrhage volume assessment: comparison of fully automated segmentation analysis with manual ABC/2 and semi-automated measurement. Eur Stroke J 2026.
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